Scientists have discovered a hitherto unknown space molecule while probing a relatively nearby region of intense star formation, a cosmic point about 5,550 light-years away. It is part of the Cat’s Paw Nebula, also known as NGC 6334.
The team, led by Zachary Fried, a graduate student at the Massachusetts Institute of Technology (MIT), examined a section of the nebula known as NGC 6334I with the Atacama Large Millimeter/submillimeter Array (ALMA). This revealed the presence of a complex molecule known as 2-methoxyethanol, which had never before been seen in the natural world, although its properties had been simulated in laboratories on Earth.
The discovery of the 2-methoxyethanol molecule was remarkable. It contains 13 atoms, which may not sound like a lot, but only six molecules have been discovered in space with an atom count beyond that. This molecule also represents the largest and most complex “methoxy” molecule found in space to date, referring to a chemical with a methyl group atom attached to an oxygen atom.
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“Our group tries to understand which molecules are present in the regions of space where stars and solar systems will eventually form,” Fried said. “This allows us to piece together how chemistry evolves along with the process of star and planet formation.”
Interestingly, the same team also hunted for 2-methoxyethanol in another region of space called IRAS 16293-2422B, home to four newborn protostars located in the star-forming region of Rho Ophiuchi located about 359 light-years away. we. This may hint at more diversity in the chemical composition of star-forming regions.
ALMA knew what to look for in a cat’s paw
Fried and colleagues did not enter the investigation of NGC 6334I and IRAS 16293-2422B without any basis. They already had a good idea of the molecule they would be looking for with ALMA, an array of 66 radio telescopes located in the Atacama Desert in northern Chile. Basically, they took a tip from machine learning models that suggested they hunt for 2-methoxyethanol.
The group then measured and analyzed the rotational spectrum of 2-methoxyethanol on Earth, which Fried described as “the unique patterns of light they emit as they fall into space.”
“These patterns are fingerprints or barcodes for molecules,” the MIT researcher added. “To detect new molecules in space, we first have to have an idea of what molecule we want to look for, then we can record its spectrum in the lab here on Earth, and finally look for that spectrum in space by used telescopes.
“Barcode Matched!”
“Ultimately, we observed 25 spin lines of 2-methoxyethanol that aligned with the observed molecular signal toward NGC 6334I, thus resulting in a confident detection of 2-methoxyethanol in this source,” Fried said.
This successful discovery then allowed the team to deduce the physical parameters of the molecule associated with NGC 6334I, including the abundance at which it exists and the molecule’s excitation temperature.
“It also enabled an investigation of possible pathways of chemical formation from known interstellar precursors,” added Fried.
Such discoveries allow scientists to better understand how increasingly complex molecules emerge during star formation, as well as when planets begin to coalesce around those stars.
“Continued observations of large molecules and subsequent derivations of their abundances allow us to advance our knowledge of how efficiently large molecules can be formed and by which specific reactions they can be produced,” concluded Fried. “Furthermore, since we detected this molecule in NGC 6334I but not in IRAS 16293-2422B, we were presented with a unique opportunity to see how the different physical conditions of these two sources may affect the chemistry that may occur. “
The team’s research was published April 12 in The Astrophysical Journal Letters.
